se·ri·ous (sîr-s)
adj.
1. Grave in quality or manner: gave me a serious look.
2.
a. Carried out in earnest: engaged in serious drinking; serious study of Italian.
b. Deeply interested or involved: a serious card player.
c. Designed for and addressing grave and earnest tastes: serious art; serious music.
d. Not trifling or jesting: I'm serious: we expect you to complete the assignment on time. Her question was serious enough to deserve a thoughtful response.
e. Of considerable size or scope; substantial: a cleanup that cost serious money.
f. Of such character or quality as to appeal to the expert, the connoisseur, or the sophisticate: "Every serious kitchen needs at least one peppermill" Washington Post.
3. Concerned with important rather than trivial matters: a serious student of history.
4.
a. Being of such import as to cause anxiety: serious injuries; a serious turn of events.
b. Too complex to be easily answered or solved: raised some serious objections to the proposal.
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[Middle English, from Old French serieux, from Late Latin srisus, from Latin srius.]
http://www.thefreedictionary.com/seriousDang, never thot I'd see sumthin that serus in this place.